Okay thanks Peter, I will relay this to the user. People are having trouble from both mobile and desktop, at different (albeit random) intervals.
I found this on the web on Nortons site, which specifically notes a change that Let's Encrypt made at the end of last year, possibly affecting older devices. Do you think this could be the issue?
Article link - How to fix a “Your connection is not private” error | NortonLifeLock
What is the “Your connection is not private” error?
A “your connection is not private” error means your browser cannot verify whether a website is safe to visit. Your browser issues this warning message to prevent you from visiting the site, because visiting an unsafe or unsecure site may put your personal information at risk.
Your browser verifies a site's security certificate to confirm the site will protect your privacy while visiting it. If a certificate is not up to standard, this means your personal data might not be encrypted and therefore susceptible to online threats. In short, a "your connection is not private" error means just that: Your connection is not private, and the error isn't something to ignore.
The “Your connection is not private” error made headlines in September 2021, thanks to the scheduled expiration of the digital certificates issued by Let’s Encrypt.
Let's Encrypt is one of the biggest issuers of the HTTPS certificates that encrypt or scramble the connections between your smartphones, laptops and other devices and the Internet. These certificates and the encryption they provide ensure that snoops can't steal your data as you search the web.
Thanks to these certificates, cybercriminals can't read your log-in information when you connect to your online bank, snatch your passwords when you sign into your online credit card portal or snoop on emails between you and your healthcare providers.
In late September, though, Let's Encrypt saw its root certificate expire. Those relying on older devices to connect to the Internet, then, might have seen an increase in the number of "Your connection is not private" errors as they searched the web.
The root certificate that Let's Encrypt uses — known as the IdentTrust DST Root CA X3 — was scheduled to expire on September 30, which it did. Because of this, computers, devices, and browsers after this date no longer trust the certificates that had been issued by Let's Encrypt. Tech experts say this wouldn’t cause problems for most consumers. But they did say that devices running older software, such as older model smartphones, are most likely to see more “Your connection is not private” errors because of the Let’s Encrypt certificate expiration.